Apple M3 Pro, MacBook Pro - USB-C to DisplayPort not working

The specs have been tightened, and some setups are no longer adequate.

More recent versions of MacOS appear to be more demanding that NO errors occur in transmission to the display. Cables that used to work may no longer work.

Thanks, caulbach, the information helped in fixing the issue with my extended displays 30" AOC gaming monitors. i am using the below configuration to make it work.

Apple M3 Pro.

2560X1440 both monitors supporting 120 Hertz.

using Plugable Thunderbolt™ and USB-C Dual Monitor Docking Station, 96W Lapt – Plugable Technologies \

this extender from 3yrs for previous version on M2 and now with m3 working perfect no issues.

they have latest version, but I don't need for now. Happy i am back online.

hope it helps,

Mr. Tea Bag wrote:

I just plugged my Samsung monitor into my new M3 MacBook Pro via HDMI and it straight up doesn't work. Isn't even recognised.

You have camped on the end of a discussion with more than 60 posts. If your problem is the same, your solution might be found by re-reading some of this posts above. Readers are NOT likely to find your posting here, this discussion is already too long. Please start a new discussion:

Start a new Discussion

.

You have camped on the end of a discussion with more than 60 posts. If your problem is the same, you should find your solution by re-reading some of this posts above. Readers are NOT likely to find your posting here, this discussion is already too long. Please start a new discussion:

Start a new Discussion

.

The main issue of the original discussion was resolved by using appropriately short cables.

¿are your cables appropriately short?

@nerukner-

2560 by 1440p displays at up to about 120 Hz fit inside the 20 G bits/sec requirement of USB-C 3.2. They use what is called HBR-2 which requires 17.28 G bits/sec.

That high speed requires a USB port that can 'turn around' the inbound data pathways and use them for outbound data part of every screen refresh, at least 60 times a second.

straight USB-C cables required are certified to at least USB-C SuperSpeed PLUS, and show this logo, and are one meter or shorter:

An adapter/cable to DisplayPort should have one meter or less before the bulge of the adapter circuitry.

at those data rates, you can't put hardly anything else on that cable except slow-speed devices.

Hey I had the exact same issue as you and purchasing a 1m cable fixed the issue instantly.

I believe the cable you linked 6.6ft so that would explain the issue.

EDITED: 🤦‍♂️

Guys/Gilrs! Just to say, its working...

After I read all messages of this thread, I give a second chance. I un-managed all my Dell cables and connected one only cable (DP to MiniDP) from Dell (curiously thinner than others) to my USB-C -> miniDisplayPort Adapter. And connected flowlessly and at 120Hz.

And with this adaptor that even was only mention 4k 60HZ.

https://pt.aliexpress.com/item/1005001858199340.html

was:

Just to share my pain, my previous MacBook Pro 15 i7 from 2015 I even connected 3 monitors, 1 hdmi and 2 minidisplayport... yeah.

But until late 2022/23 I worked with my old MacBook Pro with a Dell 3440x1440 @ 120Hz monitor via mini display port. Neat.

Now with the this new MacBook Pro M3Pro it's a disappointment, I can only connect by hdmi, which on this monitor, only makes 50Hz... I've already tried some usbc adapters for minidisplayport and nothing. Not even image. Every other PC computers or old Macs work in this dell. Except this M3... so frustrating.

high end display data rates use dual-rail logic and are approaching the maximum switching speeds of digital logic. USB cables for high-end displays need to be one meter or SHORTER.

Your first cable is two meters. Does not work reliably in later version of MacOS

Your second cable is one meter.

So this is a “feature” and not a bug? That’s sad to hear. The monitor is able to be driven to 1440p 165 Hz, but I can’t seem to go above 144 Hz with my HDMI cables. I also can’t seem to find any DP cables in my home that will work either (I have the Amazon Basics cable the other user posted about as well). I’m also not totally sold that this is purposeful yet. Upon looking at the Asahi community I see a few posts discussing how Apple broke many settings with regards to external displays with the 14.1.1 update.

specs I found HERE say:

2560 by 1440 display

Connectivity

HDMI 2.0 x2,

Display port 1.2 x1 (capable for HDR)

DisplayPort 1.2 says No Display Stream Compression, so the raw bit rate can not be exceeded, and is limited to HBR2 at 17.28 g bits/sec, VERY close to the limits for USB at 20 G bits/sec, and requiring the interface to 'turn around' the inbound conductors and use all conductors momentarily for outbound transmission. that also causes additional switching noise on the cable.

Anything short of an excellent cable/adapter will fall apart at those speeds.

HDMI cables you want for HDMI-only Displays (higher resolutions than 720p TV sets) are marked as Certified with an anti-counterfeiting tag and are labeled:

"Premium High Speed HDMI cable" or that + "with Ethernet" --OR--

"Ultra High Speed HDMI cable" or that + "48G"

Cables with No Certification tags are good for your standard 720p TV set, and not much more.

HDMI was invented for HD TV sets. it works great at its original resolution of 720i or 720p. At higher resolutions, it quickly develops issues that are complex to solve, and the cables and adapters required to solve are NOT intuitive.

--------

Your display features TWO HDMI inputs. IF the display also supports Picture-By-Picture (cousin of Picture-in-Picture), you can connect to the display with TWO HDMI cables, each driving left or right half-display, and the display puts the halves back together at far higher speeds than a single cable can support. Yes, one can be provided with an adapter if needed.

On the Mac, both half-displays are treated as as parts of a seamless "Extended Desktop" -- well supported by MacOS since about 1987. Invisible to well-behaved software.

Edit: the manual suggests that with the added software, you CAN configure Picture-By-Picture.

RE: USb cables

Ordinary USB cables are usually considered strictly local peripheral cables, and are not good enough to allow a computer-to-computer networking connection, such as File Sharing between computers.

That you ever got it to work with anything short of a Thunderbolt cable is remarkable.

Yes, it’s a USB-C that I usually just use for charging. It actually worked multiple times. I first used it for a migration from my old intel MBP to a 14” M3 Pro MBP. Then, I used it to migrate from the 14” M3 Pro to a 16” M3 Pro. It worked flawlessly both times with a transfer speed of about 1700 mb/s. After updating the 16” M3 Pro to 14.1.1, I had to to do the migration again and the same cable was no longer working.

Hi, my cable is this "https://articulo.mercadolibre.com.co/MCO-1336100265-cable-usb-c-displayport-dp-14-gamer-8k-4k-2k-1-metro-1m-_JM?matt_tool=46217434&matt_word=&matt_source=google&matt_campaign_id=14634237767&matt_ad_group_id=145708769512&matt_match_type=&matt_network=g&matt_device=c&matt_creative=644763067375&matt_keyword=&matt_ad_position=&matt_ad_type=pla&matt_merchant_id=5079124814&matt_product_id=MCO1336100265&matt_product_partition_id=2186001721843&matt_target_id=aud-2200363567910:pla-2186001721843&gad_source=1&gclid=CjwKCAiAqNSsBhAvEiwAn_tmxX1Jv5HkDkITl6n0F1mLuo_os8lIbfBZRT9cYAUsb7IVroGkjsmCfRoCzG0QAvD_BwE" but does not work with mbp m3 and sonoma 14.2.1......this is so sad.